Im looking at changing the two 8D start batteries to 4 group 31s. My batteries are stacked on two slides in the compartment. It doesnt look like two 31s will fit in the same area that a 8D is. Im curious how anyone else has done this......

I replaced 2 8D's with 2 Group 31"s and have had no starting problems. I do try to stay out of cold weather and will use my block heater if it is less than 40 degrees out. I also have a rebuilt 8V71 that only has about 50,000 miles on it so it usually fires up as soon as i hit the switch.

I also use two group 31 batteries to start our 8V92. When one failed the guy at the battery store (they only sell batteries, mostly wholesale) suggested a used one to go with the good used one I had. So for a small fee I have a good working pair again. I don't know how long they will last, but they won't leave me stranded because I can also start off of the new six battery house bank if needed.Good luck, Sam MC8